Durable press characteristics are imparted to cellulose-containing fabrics by various cross-linking agents and resin formulations which cross-link the cellulose molecules. The widely-used cross-linking agents based upon formaldehyde are sometimes found objectionable for health and environmental reasons and attempts have therefore been made to replace them with formaldehyde-free cross-linkers. Butanetetracarboxylic acid (BTCA) is a carboxylic acid based resin investigated extensively in the cross-linking of cellulose for durable press resin finishes. Rowland and co-workers at the U.S. Department of Agriculture's Southern Regional Research Center have published widely on this subject.
U.S. Pat. No. 3,526,048 to Rowland et al refers to the cross-linking of cellulose with a variety of polycarboxylic acids, including BTCA, partially neutralized with an alkali metal hydroxide, ammonium hydroxide or an amine.
U.S. Pat. No. 4,820,307, to Welch et al, describes the reaction of cellulose with BTCA and a wide variety of other polycarboxylic acids, using a variety of phosphorus-containing catalysts, to produce durable press cellulosic fabrics.
WO 89/12714 (1989), also to Welch et al, describes the treatment of cellulose with a polycarboxylic acid and a "curing catalyst" selected from alkali metal hypophosphites (preferably), phosphites and polyphosphates.
These documents feature the use of phosphorus-containing catalysts, notably alkali hypophosphites, in fairly large amounts. The use of phosphorus-containing chemicals creates environmental concern in areas where phosphorus content of effluents must be carefully controlled.
We have discovered and hereby disclose a class of chemicals, described generally as cyanamide compounds, as more fully explained below, that effectively catalyze the formation of esters between polycarboxylic acids, including BTCA and other polycarboxylic acids that can be used in durable press finishes for cellulose-containing fabrics, and polyols like cellulose.